Initially it shall be explained that the term “vacuum” as used in this description shall be understood as a pressure below ambient atmospheric pressure and which is effective to produce between the suction cup and the object the holding force that is required to fixate, to lift and to move the object. The term vacuum shall thus be understood in a broader sense than in terms of an absolute pressure-less condition.
A negative pressure for driving a tool with a suction cup according to the invention can be provided using a motor-driven pump or a compressed air driven ejector in a manner known per se. The negative pressure is typically discharged to a suction cup which is supported by a tool, such as a lifting means which is arranged mobile and operated and controlled for lifting and moving of an object, or by a tool that is designed to keep the object fixed in a certain position. In many applications it is advantageous to arrange a flexible bellows between the tool and the suction cup, such as when a particularly gentle application of the suction cup to the object is desirable or if the object's surface is uneven and has level differences.
Suction cups of this type which are fitted with bellows are often made with a sealing surface formed integrally with the bellows and brought into sealing contact with the surface of the object. This sealing surface is subjected to wear, and shall in respect of its properties such as softness, flexibility and ability not to impose marks on the object be adapted to the subject object. The properties of the sealing surface therefore often differ from the desired properties of the bellows in the form of elasticity combined with strength and stability. The desired characteristics of the bellows and the sealing surface can be integrated into an individual suction cup through a double-casting process, e.g., which at the same time results in that the entire suction cup must be discarded when the sealing surface is worn out, or needs to be replaced by another suction cup upon a change in production, e.g.